Marion Dougherty came to New York from Pennsylvania in 1944 with dreams of becoming a theater set designer. While waiting for her big break, she worked for $45 a week designing windows at Bergdorf Goodman. But Dougherty’s break came in a different form a few years later when a friend working at the NBC live anthology series “Kraft Television Theater” asked her to become a casting assistant on the show.

In time, Dougherty would transform â€” and in many ways invent â€” the role of casting director that made her a legend in New York and Hollywood.

The new documentary “Casting By,” airing at 9 p.m. Monday on HBO, focuses on Dougherty and another casting pioneer, Lynn Stalmaster. Directed by Tom Donahue, “Casting By” is ultimately a love letter to Dougherty, who died two years ago at age 88, and the art of casting.

Juliet Taylor, a well-known casting director who worked with her early in her career, said Dougherty took a firm, blunt approach to casting â€” and to directors.

“She would tell directors, ‘I just want you to know I am not going to bring in 10 or 20 people for every part. I am going to bring in three or four people, and each one is going to be very different,’ ” Taylor recalled. “She in a way had to discipline the directors into a new kind of process, a very selective process rather than just throwing a lot of people in front of them in a more general way.”

Donahue captured Dougherty’s colorful personality during the 12 hours of interviews he did with her in 2007. “My jaw dropped,” he recalled, as she regaled him with stories of the actors to whom she gave their start, including James Dean, Warren Beatty, Jon Voight and Glenn Close.

The documentary features amusing and sometimes-emotional interviews with stars such as Bette Midler, Al Pacino and Dustin Hoffman, who talk about the effect Dougherty had on their lives when no one else believed in them. She had an eye for seeing talent before it fully blossomed, like that of Voight, who was a disaster in a guest stint on the ABC series “Naked City,” which Dougherty cast. But she fought to cast him as Joe Buck in 1969’s “Midnight Cowboy,” which won an Oscar for best film.

The documentary features interviews with several highly regarded casting directors she mentored, including Taylor â€” who has cast every Woody Allen film since 1975’s Love and Death” â€” Ellen Lewis and Wallis Nicita. Also interviewed are such filmmakers as Allen, Clint Eastwood and Martin Scorsese, who says that “more than 90% of directing a picture is the right casting.”

She also fought for the profession to gain respect in the industry. She would have been pleased that last week the board of the Academy of Motion Picture Arts and Sciences approved the creation of a Casting Directors Branch. Casting directors began to be invited to academy membership more than 30 years ago, many of them admitted as members-at-large, but there had not been a separate branch. And unlike the Emmys, no Oscars are given out for casting directors.

Before Dougherty, said Taylor, studios’ casting departments had a grocery list of actors under contract whom they would use for projects. “If a part was written for a certain type of gal, they would bring in 20 short blonds,” noted Taylor. “They wouldn’t think about what you could do to make it a little less expected or bring a little more depth to it.”

Donahue said Dougherty was at the right place at the right time. She was in New York at a golden age for small theater, where she discovered many future stars. Because she was an outsider, he said, “She was able to bring [casting] into a new perspective. She had complete power to find somebody off-Broadway, bring them in and put them on TV. Nobody said yes or no to her choices. Television was so new and fast, I don’t know if anybody had the skill sets to really supervise her.”

After casting such TV series as “Kraft,” “Naked City” and “Route 66,” Dougherty segued to feature films with George Roy Hill’s “The World of Henry Orient” (1964). She subsequently cast all of the director’s films, including the Oscar-winning “The Sting” (1973).

“She and George had a shorthand, which is what I have with Woody when you work together so many years,” said Taylor. “They understood each other. An idea would strike Marion and she would bring it up and George would light up.”

She opened her first casting office, Marion Dougherty Associates, in a restored brownstone, in 1965. It was known as “the brothel” because all the employees were women and their clients were men.

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After a divorce, Dougherty came to Hollywood in the early 1970s and was head of casting at Paramount Pictures and later at Warner Bros. She retired in 1999.

When Dougherty left New York, Taylor, then 25, took over the casting of Allen’s movies. For years, Taylor didn’t know Dougherty had recommended her to Allen. “I thought he was just too scared because he didn’t like to meet new people,” said Taylor. “Marion was supportive like that.”